Tone chamber



Patented Jan. 25, 1927.

UNITED STATES PATENT OFFICE.

PAUL B. ARMSTRONG, OF CHICAGO, ILLINOIS, ASSIGNOR TO CLARA S. ARMSTRONG, O

CHICAGO,

ILLINOIS.

TONE CHAMBER.

Application filed December 3, 1924. Serial No. 753,564.

My invention relates to tone chambers or amplifiers for use in connection with the reproduction of sound waves. One of the principal objects of my invention resides in providing a simple structure that will an plify the sound waves from mechanical reproducers such as the reproducer used in a phonograph or the'amplifying device employed in connection with radios. In this connection I have provided a tone'chamber which, besides having the amplifying char-' acteristic, will also qualify and naturalize the sound waves and thereby eliminate to a large degree the harsh and metallic sounds heretofore created in devices for the mechanical reproduction of sound waves. In carrying out my invention I have provided a box or enclosure in which is mounted a tone chamber or amplifier which includes among other things the upper and lower walls that are of a resonant character and which are formed of compound curves that closely approach the curvature of the upper and lower portions of a human mouth, and interposed between these walls I have provided an intermediately' positioned sound-board 0f the curvature of the human tongue which sound-board is unsupported at its forward and rear portions and is spaced from preferably the lower wall a distance to provide a resonant chamber to receive the sound waves and discharge them in a qualified and naturalized condition at the mouth of the horn. I

Further objects of my invention reside in providing a structure of the foregoing charactor that is simple in construction; is formed of a minimum of parts; is effective and dependable in operation; and which is novel and sturdy in construction. I accomplish the foregoing objects and prefer to carry out my invention in substantially the manner hereinafter fully described and as more particularly pointed out in the claims, reference being had to the accompanying drawings that form a part of this specifica' ti on, in which Fig. 1 is a front elevation of my tone chamber with the grille of the enclosing box removed.

Fig. 2 is a. vertical longitudinal section thereof.

Fig. 3 is a transverse vertical section on lines 33 of Figure 2 lookin'g'towards the rear of the structure.

Fig. 4 is a horizontal longitudinal section on line 4 1 of Fig. 3 looking towards the bottom of the structure.

In the drawings 10 designates the vertical longitudinal side-walls of a casing or housing which is provided with top and bottom walls 11 and 1.2 represpectively and with a rear wall 13 that is hinged on its lower edge to the rearedge of the bottom wall 12 so that a suitable door is provided for access to the interior of the case. An open-work grille 14 is positioned at the front end of the case in the usual manner of such elements in phonographs, talking machines, and the like.

Spaced slightly from the rear wall or door 13 is an upright standard or support 15 that extends from the top wall 11 to the bottom wall 12 of the casing but is spaced from the side walls 10 of the casing. Suitable cleats 16 assist in rigidly mounting this standard and are secured to the top and bottom walls, as seen in Figure 2, and extend from sidewall'to side-wall in a horizontal direction, as seen in Figures 3 and 4.

A base plate 17 of rectangular shape is secured to the forward face of the standard 15 and said base is provided with an aperture 18 aligning with the aperture 19 in the base plate 15, and the latter is of such dimensions as to receive th discharge tube 20 of an amplifying unit 21 of any suitable type when the structure is used in connection with radio reproduction. When my device is used for reproduction from a phonograph the aperture 19 communicates with a tube leading from the tone arm of a phonograph in the usual manner. A suitable rectangular shaped holder 22 surrounds the aperture 18 in the base and has its internal. surface slightly tapered, as seen in Figures 2 and 4, so as to receive the adjacent end of the tone horn which will now be described.

The vertical side-walls of the horn consist of wood plates 23 that converge towards the holder 22, and their inner ends are suitably connected to the latter in the central aperture formed by the holder. Besides converging towards each other the side walls 23 are reduced in height or tapered towards the sound aperture, as seen in the side elevation in Figure 2 of the drawings, and their upper and lower edges are formed with a compound curve, as will be observed. The curvature of the upper and lower edges of these side-walls determines the shape of the upper and lower portions or walls of the horn, and secured to said upper and lower edges are the thin horizontal resonant walls 2% and respectively, that extend from one side-wall to the other and are secured to the undulatingedges thereof. The upper wall 2%: extends from the forward end of the horn, which is adjacent or immediately back of the. grille 14, in an upwardly curved direction as at a, changes to a compound curve adjacent the top wall 11 of the box or usin and it then curves downwardly in a eep 6 toward the holder 22, and its portion merges into a reverse curve the contorniation is very similar to oi the human -aouth. The lower resonant wall 25 extends from near the grille 1d downwardly in a curve a toward the bottom wall 12 of the casing and then extends upwardly as at toward tae rear and merges into a reverse curve 0 to the location of the holder 22, and the conformation of this curve is similar to the upper curve but in a reverse direction and corresponds in shape with the curvature of the lower portion of the human mouth. Intermediate the top and bottom resonant walls is a sounding board 26 which extends from the rear of the horn forwardly :t'rom side-wall to side-wall to about the transverse plane where the curves of the top and bottom resonant walls 2% and merge into their reverse curves (or about one-half the length of the horn), and from this point forwardly the tongue slopes in a downwardly direction to a point alongside the vertical plane of the forward end of the horn where it rests upon a cross piece 27.

At a point located about the greatest bulge of the horn in a vertical direction the intermediate resonantwall or tongue 26 is provided with an aperture 28 that is elongated in a transverse direction, as seen in Figure l-, and back o1 said aperture is a transverse rail 29. A vertical post 30 extcnds from the transverse rail to the lower or bottom resonant wall 25 of the horn in the manner shown in the drawings and conuects the resonant tongue member 26 with the lower resonant wall 25.

From the foregoing it will be seen that the sound waves emanating from the reproducer or other instrumentconnected with the aperture 19 will be discharged into the smaller end or the horn and will have a straight-away path through the horn be tween the sounding-board 26 and the upper resonant wall 2 as indicated by the arrows in Figure 2 of the drawings. Thus there will be no obstruction to the path of these sound waves. The placing of aperture 28 in the sounding-board at the location of the greatest bulge in the horn prevents the prime or fundamental tones, without destroying its capacity to vibrate sympathetically with every tone wave passing over the sensitive resonant surface, thus augmenting and naturalizing the quality of the tones produced and absorbing or deadening the metallic tone waves which usually emanate from reproducers during the mechanical reproduction of sound. lhe acoustics oi the tone chainhcr or horn are such that ittle or none of the inechan'cal sounds reach the ears of the hearers or audience who may be listening to the reproduction in front ot or adjacent the structure, and the volume of the tones produced or amplified by the structure is matei-fially increa ed. 'lhe shape of the upper and lower walls and the sound-board, being practically duplicates on an exaggerated scale, or the root and lower portion of the human mouth and the shape of the human tongue, have a stro g influence upon the tone waves or sound waves received in reproducing said sound wires in a natural manner but with amplified force.

1. A tone chamber comprising non-resonant side walls, upper and lower walls connected thereto and curved transversely to provide a wide bulge intermediate the ends of the horn which bulge isof greater diameter than the discharge end of said horn, and a sounding board bowed intermediate its ends in the direction of the bulge in the horn and positioned between said upper and lower walls, the receiving end of the horn being open and the sounding-board extended into said open end, whereby sound waves enter said horn upon both sides of the sounding-board.

2. A tone chamber comprising non-resonant converging side walls, upper and lower walls the planes of which bulge from each other intermediate their ends and which converge towards each other adjacent their inner ends, a sounding board spaced from the lower resonant wall and bowed longitudinally away from the same at approximately the location of the bulge, and an apertured transverse wall adjacent the converging ends of said walls for the discharge of sound waves into the horn, the location 01": the aperture in said transverse wall being such that sound waves emanating therefrom pass directly through the horn upon both sides of the sounding board without interterence.

3. A tone chamber comprising side-walls that converge towards each other to the rear there-ct, the upper edges of said walls formed in an undulating curve, top and bottom walls connecting the upper andlower edges of said side-walls and the. upper wall shaped longitudinally to conform with the upper edges of said sidewalls, and a sound-board adjacent and spaced from the bottom wall and bulged longitudinally towards the top wall, said soundboard pro- Cit vided with an aperture below the plane of travel of the direct sound-waves passingv through the upper portion of the structure, whereby a resonant chamber is provided below the axis of the structure into which sound-waves are received and from which they are discharged.

4. A tone chamber comprising a plurality of converging walls, opposite ones of which are formed longitudinally in reversed undulating curves to provide an intermediate bulge, and an apertured sound-board interposed between the latter walls and bulged longitudinally, whereby there is provided two superposed chambers open at opposite ends and disposed between opposite walls of the structure and through both of which chambers sound waves simultaneously pass without interruption.

5. A tone chamber comprising side walls,

upper and lower walls connecting the same and curved oppositely to provide a wide bulge intermediate the ends of the horn, which bulge is of greater diameter than the open egress end of the horn, and a sounding board bowed intermediate its ends in the bulged portion of the born between said upper and lower walls, said sounding board extending between the side walls and unsupported at its ends to permit the same to vibrate throughout its entire surface, the receiving end of the horn being open and the sounding board extended into said open end whereby sound waves enter said horn and pass through the same upon both sides of the sounding board.

Signed at Chicago, county of Cook and State of Illinois, this 25th day of November,

PAUL B. ARMSTRONG. 

